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PubMed1990

Differential expression of alternate forms of a Drosophila src protein during embryonic and larval tissue differentiation.

The Dsrc28C gene encodes two major proteins, p66 and p55, each of which contains a tyrosine kinase domain. Using monoclonal antibodies we have completed a detailed investigation of the spatial expression of Dsrc28C proteins during embryonic and larval development. Differentiation of a number of embryonic tissues is accompanied by the induction of Dsrc28C expression. With the exception of the developing salivary glands which express high levels of p66, developing tissues express the p55 form of Dsrc28C. Notable examples are cells of the and peripheral nervous systems which express p55 from the early stages of neurogenesis through the remainder of embryogenesis and pole cells which transiently express p55 during portions of embryonic stages 10 and 11. Nervous system expression includes the cell bodies and neuronal fibers of the central nervous system, the anterior sensory organs, and the peripheral sensory neurons. During larval development, p55 levels within the central nervous system remain high but substantial changes in the pattern of expression take place. p55 gradually disappears from the neuronal fibers of the central nervous system and from embryonic cell bodies. During the third larval instar, the birth of immature neuroblasts within the ventral and midbrain ganglia, but not within the optic ganglia, is marked by a transient high level of p55 expression. All imaginal cells that have been observed within the larva express the p66 protein. The patterns of expression that we have noted suggest that expression of the p55 form of Dsrc28C protein is an early event in the differentiation of neuronal cells, while expression of the p66 form is characteristic of cells committed to ectodermal cell differentiation.

Animals↗
PubMed1985

Immunofluorescent detection and localization of thyroxine in blood of Rana catesbeiana from early larval through metamorphic stages.

Indirect immunofluorescent staining was used to detect and localize thyroxine (T4) in blood smears from individual Rana catesbeiana tadpoles in almost every stage of larval development. Earlier radioimmunoassays revealed a surge of T4 in the blood plasma during metamorphic stages, but plasma T4 concentrations in earlier stages were either very low or below the minimal detectable limits of the assays. With the present immunofluorescent method, T4 was found in plasma of tadpoles throughout the entire larval period from early limb bud stages to the end of metamorphosis. Moreover, T4 was also found in association with cytoplasm and nuclei of red blood cells, particularly nuclei of the new population of adult red cells differentiating during metamorphic stages. In conclusion, thyroid hormone is present in both blood plasma and erythrocytes of R. catesbeiana from early through late stages of larval development.

Animals↗
PubMed2001

Effects of 4-n-nonylphenol and 17beta-oestradiol on early development of the barnacle Elminius modestus.

Pollutants that are present in the aquatic environment and cause abnormal endocrine function in wildlife populations have been termed endocrine disrupting chemicals (EDCs). The impacts of these chemicals on the reproduction and development of vertebrates has been shown to be significant in both field studies and laboratory experiments. Over the past decade the number of investigations into the impacts of EDCs that affect reproductive and sexual characteristics (reproductive EDCs) has increased and evidence of their potency is evident in numerous wildlife species and through data from in vitro tests. However, little information is available on whether chemicals which act as EDCs in vertebrate species affect aquatic invertebrates. The case of imposex in archeogastropods following exposure to tributyltin (TBT) is a notable exception. Moreover, a number of studies have shown that development, fecundity and reproductive output of some aquatic invertebrates are affected significantly by exposure to pollutants. In order to determine whether external signs of exposure to vertebrate EDCs can be observed and monitored in invertebrate species, we exposed larvae of the barnacle Elminius modestus to environmentally realistic concentrations of the xeno-oestrogen, 4-n-nonylphenol (NP), and the natural oestrogen, 17beta-oestradiol (E(2)). Early life stages (nauplii and cyprids) were also exposed in the laboratory to determine whether there were effects on the timing of larval development and settlement. Ovary development and size of juveniles was measured following chronic exposure. Exposure to NP in the concentration range 0.01-10 µg l(-1) resulted in disruption of the timing of larval development. Similar results were obtained with E(2). Pulse exposures showed that the timing of exposure is critical and exposures for a period of 12 months caused long-term effects. A linear, concentration-dependent response was not evident.

Journal Article↗
PubMed1984

During frog ontogeny, PHA and Con A responsiveness of splenocytes precedes that of thymocytes.

The in-vitro proliferation of splenocytes and thymocytes from Xenopus laevis-gilli (hybrid clone LG-15) to the T cell mitogens, concanavalin A (Con A) and phytohaemagglutinin-P (PHA), were examined at specific stages of larval development (stages 51-66 of Nieuwkoop & Faber, 1967) and at 2 months post-metamorphosis. The responses of splenic lymphocytes to each mitogen were significant at all stages with stimulation indices ranging from 1.9 to 50.5 and 2.6 to 45.5 for PHA and Con A, respectively. Stage-related differences in responses of splenocytes to both mitogens suggest two waves of emergence of proliferative activity during development, divided by periods of diminished responsiveness during the metamorphic crisis. In contrast to the responses observed with splenocytes, proliferation of thymocytes cultured with either mitogen was barely detectable, with stimulation indices ranging from 1.2 to 6.9 and 1.4 to 2.9 for PHA and Con A, respectively. These minimal responses were observed only when thymocytes were cultured at relatively high cell density (5 X 10(5) cells/ml); they were not improved by increased or decreased concentrations of mitogen or by increased concentrations of fetal calf serum (5 or 10%) in the medium. Co-culture of larval thymocytes with autologous splenocytes and each mitogen did not consistently increase thymocyte responses suggesting that the defect in thymocyte responsiveness is not due to lack of accessory cells. These findings suggest that if PHA- and Con A-reactive cells are present in the thymus, they are present in relatively low numbers at all stages of larval development. The pattern of early mitogen responsiveness in the spleen at a time when the thymus is unresponsive contrasts with that observed in mammalian development in which thymocytes become responsive to mitogens in fetal stages and mitogen responsiveness appears in the spleen only around the time of birth. The apparent inactivity of larval thymocytes may reflect a population of cells that can become tolerant to those neo-self-antigens that arise during and after metamorphosis. If so, the larval amphibian thymus may provide a model to study the early events of thymocyte 'education' and differentiation in a broader time framework than is possible with fetal mammals.

Animals↗
PubMed2004

Utilization of blueberry by the lappet moth, Streblote panda Hübner (Lepidoptera: Lasiocampidae): survival, development, and larval performance.

The lappet moth, Streblote panda Hübner [1820] (Lasiocampidae), is a common species found in blueberry, Vaccinium spp. (Ericaceae) fields of Western Andalusia. The biology of this species as well as the extent to which its larvae can use and survive on blueberry is unknown. In this study, the suitability to larvae of several blueberry cultivars was studied. Larvae were grown under controlled laboratory conditions on excised foliage of six blueberry cultivars. Survival, development, and food use were determined for first and fifth instars. According to our results, blueberry has become an alternative host plant for S. panda in southwestern Andalusia. Low growth rates and efficiencies of use of food were observed. Lower gross efficiency of growth was found for larvae fed blueberry 'Sharpblue', despite a higher apparent digestibility of this cultivar. Larvae reared on this cultivar had the highest mortality, increased developmental time, and used a greater part of metabolism for maintenance. Herbivore pressure may be increased with the widespread planting of the most suitable cultivars 'Misty' and 'O'Neal', whereas 'Sharpblue' and'Climax' seem to be the least suitable host plants. These data provide useful information for planning and managing blueberry orchards in the presence of S. panda populations.

Animals↗
PubMed2006

Tissue distribution, effects of salinity acclimation, and ontogeny of aquaporin 3 in the marine teleost, silver sea bream (Sparus sarba).

The purpose of the present study was to ascertain the tissue-specific expression of the water channel protein, aquaporin 3 (AQP3), during salinity acclimation and larval development of silver sea bream (Sparus sarba). A cDNA fragment encoding aquaporin 3 (aqp3) from silver sea bream gill was cloned and from the deduced amino acid sequence a polyclonal antibody was prepared. AQP3 was found to be present in gill, kidney, liver, brain, heart, and spleen but not in whole blood. The abundance of AQP3 was significantly highest in gills of hypoosmotic (6 ppt) and isoosmotic (12 ppt) acclimated sea bream when compared to seawater (33 ppt) and hypersaline (50 ppt)- acclimated sea bream. Spleen tissue also displayed significantly high levels of AQP3 protein in hypoosmotic and isoosmotic salinities whereas the AQP3 abundance in brain, liver, heart, and kidney remained unchanged across the range of salinities tested. The ontogenetic profile of AQP3 was also investigated from developing sea bream larvae and AQP3 was first detected at 14 days posthatch (dph) and increased steadily up to 28-46 dph. In conclusion, this study has demonstrated that AQP3 expression is modulated in gill and spleen tissue of salinity acclimated sea bream and that it can be detected relatively early during larval development.

Acclimatization↗
PubMed1998

Histochemical study of skin and gills of Senegal sole, Solea senegalensis larvae and adults.

A battery of horseradish peroxidase-conjugated lectins (Con A, WGA and DBA), as well as conventional histochemical techniques (PAS, saponification, Alcian Blue pH 0.1, 1, 2.5, chlorhydric hydrolisis, neuraminidase, Bromophenol blue, Tioglycollate reduction and Ferric-ferricyanide-FeIII) were used to study the content and distribution of carbohydrates, proteins and glycoconjugate sugar residues on the skin and gills of Senegal sole, Solea senegalensis larvae and adults: During larval development of Solea senegalensis (from hatching until day 45 posthatching), epidermal sacciform, as well as branchial and epidermal chloride cells were unreactive with all cytochemical tests performed in this paper. Mucous or goblet cells of the corporal skin and gills containing strongly sulphated acid glycoproteins were evident on days 15-20 of larval development, as well as in epidermal and branchial mucous cells of adult specimens, which also contained GlcNAc and/or sialic acid. In adult specimen, the proteic content was higher in branchial mucous cells than in epidermal cells. In larvae, variable amounts of glycoproteins containing sialic acid, GlcNAc, GalNAc, Man and/or Glc residues were observed in epithelial cells and/or cuticle. GlcNAc and/or sialic acid sugar residues were only weakly detected in glycoproteins of some epidermal and branchial mucous cells of larvae by day 45, because from hatching until metamorphosis, lectin reactions (WGA, Con A and DBA) were negative in mucous cells.

Animals↗
PubMed1993

Effect of biotic and abiotic factors on pupation height in four species of Drosophila.

Effect of different biotic and abiotic factors such as sex, density, larval development time, moisture, temperature and light on pupation height were tested in Drosophila ananassae, D. bipectinata, D. malerkotliana and D. biarmipes which are commonly distributed in India. In the four species there are no sex differences in pupation height. Density of larvae and moisture content of food medium strongly influence pupation height. Larval development time, light and temperature also affect pupation height but there are intra- and interspecific variations in response to these factors for pupation site preference. Thus pupation site preference in these Indian species of Drosophila is influenced by various biotic and abiotic factors. The comparison of the present results with those found in other species clearly indicates that different species may vary in their response to different factors.

Animals↗
PubMed2006

Developmental stages and germ cell lineage of the loach (Misgurnus anguillicaudatus).

The staging of embryonic and larval development, and the germ cell lineage of the loach, Misgurnus anguillicaudatus, are described. Fertilized eggs were obtained by artificial insemination. For the convenience of detailed observation and photography of the external appearance, we use dechorionated embryos. Through a series of operations, these embryos were cultured at 20 degrees C in an incubator. Embryonic and larval development of the loach was divided into five periods: cleavage, blastula, gastrula, segmentation, and hatching. Stages were assigned within each of these periods. Developmental stages were determined and named by morphological features and somite number. The staging series were photographed and tabulated. The germ cell lineage was then elucidated by whole mount in situ hybridization of mRNA expression of the germ-cell-specific marker vasa and histological analysis. Primordial germ cells (PGCs) of the loach derived from the cleavage furrows of 8-cell stage embryos began proliferation in the late blastula period and migrated to the gonadal anlagen through a migration pathway similar to that of the zebrafish. However, it is characteristic of the loach that PGCs migrate a long distance and stay in the posterior part of the yolk-extension region.

Animals↗
PubMed2002

Molecular cloning and expression of thyroid hormone receptor alpha during salmonid development.

Thyroid hormones have been implicated as important regulators of teleost development. To gain a better understanding of the potential roles of the thyroid system in salmonids a genomic clone which encoded rainbow trout TR-alpha was isolated. This clone exhibited highest amino acid identity to Japanese flounder TR-alphaB (94%) and zebrafish TR-alpha1 (94%). Oligonucleotides were designed against the rainbow trout sequence and the complete coding region of Atlantic salmon TR-alpha was isolated by RACE-PCR. The Atlantic salmon sequence exhibited highest amino acid identity to rainbow trout TR-alpha (98%), Japanese flounder TR-alphaB (93%), and zebrafish TR-alpha1 (90%). Atlantic salmon TR-alpha exhibited the classic modular structure associated with members of the nuclear receptor superfamily and consisted of a divergent A/B domain while the DNA and ligand-binding domains were highly conserved to other teleost TR proteins. Temporal expression from the rainbow trout TR-alpha gene was monitored by semiquantitative RT-PCR at selected stages during rainbow trout embryonic and larval development. High levels of maternal transcripts were present at cleavage (Stage 6) which were rapidly degraded by gastrulation (Stage 13). Low levels of TR-alpha expression were then detected during organogenesis (Stages 20, 24, 26, 29, and 31). A peak in mRNA levels was observed at hatch (Stage 32) after which levels rose in a gradual manner during larval development (Stages 33, 34, 35, and 36) to reach maximal values at first feeding (Stage 37). These results suggest that the thyroid axis is functional and that embryonic and larval rainbow trout are at least capable of responding to thyroid hormones. These observations implicate the thyroid system as being an important regulator of salmonid development.

Amino Acid Sequence↗
PubMed1998

Incorporation of microalgae sterols by scallop Pecten maximus (L.) larvae.

Changes in sterol composition of Pecten maximus larvae during the larval development stage with standard algal mixtures and unialgal diets were analysed. The sterol composition of four microalgae currently used in mollusc hatchery were also examined. Under standard algal conditions, the larvae quickly use the steryl ester from larvae reserves during the endotrophic and the mixotrophe phases. The preferential incorporation of Pavlova lutheri and T-Isochrysis sterols, rather than Skeletonema costatum sterols, during the larval development stage would indicate that S. costatum cells were poorly ingested and digested by larvae. Among the ingested sterols, cholesterol and stigmasterol were preferentially incorporated by the larvae. Conversely, the larvae appeared able to limit the incorporation of methylpavlovol, ethylpavlovol, and 4alpha-methylporiferasterol. In the unialgal experiment, the best growths were obtained with the diet richest in cholesterol (Chaetoceros calcitrans) and the best compromise of good growth and settlement rate was observed with the diet richest in C24 ethyl sterol. The selective incorporation of the cholesterol was confirmed by the larval rearing with C. calcitrans. The strong sterol dietary imprint in larvae corroborated the absence of an important capacity in P. maximus larvae to convert or biosynthesise sterol.

Animal Feed↗
PubMed2004

Expression of the genes Emx1, Tbr1, and Eomes (Tbr2) in the telencephalon of Xenopus laevis confirms the existence of a ventral pallial division in all tetrapods.

To investigate the pallial organization and the exact location and extension of the ventral pallium in amphibians, we cloned a fragment of the homeobox XenopusTbr1 (xTbr1) gene and analyzed its expression compared with that of the genes xEomes (Tbr2) and xEmx1 in the telencephalon of the frog Xenopus laevis during embryonic and larval development. The expression of xEmx1 was also analyzed in the adult frog. We compared the expression patterns of these pallial marker genes with that of the subpallial gene xDistal-less-4 (xDll4). Our results indicate that the whole pallium of Xenopus expresses the T-box genes xTbr1 and xEomes (in proliferating cells and/or mantle) during embryonic and larval development, and the expression of these genes is topographically complementary to that of xDll4 in the subpallium. In addition to their massive expression in the pallium, both xTbr1 and xEomes are expressed in a few dispersed cells in the subpallium, which may represent immigrant cells of pallial origin, because these genes are not found in the subpallial proliferating cells. On the other hand, during development xEmx1 is expressed in a large part of the pallium (proliferating and postmitotic cells) except for an area adjacent to the pallio-subpallial boundary, where xEmx1 is observed only in some mantle cells. This pallial area poor in xEmx1 expression and poor in expression of the subpallial gene xDll4, but expressing the pallial marker genes xTbr1 and xEomes, appears to represent the amphibian ventral pallium, comparable to that described in other vertebrates (Puelles et al. [2000] J. Comp. Neurol. 424:409-438). In the adult frog, the ventral pallium appears to include the rostral part of the lateral amygdalar nucleus as well as a large part of the medial amygdalar nucleus (as defined by Marín et al. [1998] J. Comp. Neurol. 392:285-312). In contrast, the caudal part of the previously termed lateral amygdalar nucleus shows strong xEmx1 expression and may be a lateral pallial derivative. The possible homology of these amphibian amygdalar nuclei is discussed. Finally, expression of xTbr1, xEomes, and xEmx1 is observed in the mitral cell layer of the olfactory bulb from early developmental stages, further supporting that this structure is a pallial derivative.

Animals↗
PubMed2002

Carotid labyrinth of amphibians.

The amphibian carotid labyrinth is a characteristic maze-like vascular expansion at the bifurcation of the common carotid artery into the internal and external carotid arteries. The carotid labyrinths of anurans are spherical and those of urodeles are oblong. In the intervascular stroma of both anuran and urodelan carotid labyrinths, the glomus cells (type I cells, chief cells) are distributed singly or in clusters between connective tissue cells and smooth muscle cells. In fluorescence histochemistry, the glomus cells emit intense fluorescence for biogenic monoamines. In fine structure, the glomus cells are characterized by a number of dense-cored vesicles in their cytoplasm. The glomus cells have long, thin cytoplasmic processes, some of which are closely associated with smooth muscle cells, endothelial cells, and pericytes. Afferent, efferent, and reciprocal synapses are found on the glomus cells. The morphogenesis of the carotid labyrinth starts in the larvae at the point where the carotid arch descends to the internal gills. Through the early stages of larval development, the slightly expanded region of the external carotid artery becomes closely connected with the carotid arch. By the end of the foot stage, the expanded region becomes globular, and at the final stage of metamorphosis the carotid labyrinth is close to its adult form. In fine structure, the glomus cells appear as early as the initial stage of larval development. At the middle stages of development, the number of dense-cored vesicles increases remarkably. Distinct afferent synapses are found in juveniles, although efferent synapses can be seen during metamorphosis. The carotid labyrinth is innervated by nerve fibers containing several kinds of regulatory neuropeptides. Double-immunolabeling in combination with a multiple dye filter system demonstrates the coexistence of two different neuropeptides. The amphibian carotid labyrinth has been electrophysiologically confirmed to have arterial chemo- and baroreceptor functions analogous to those of the mammalian carotid body and carotid sinus. The ultrastructural characteristics of the glomus cells during and after metamorphosis suggest that the glomus cells contribute to the chemoreception after metamorphosis. The three-dimensional fine structure of vascular corrosion casts suggests that the amphibian carotid labyrinth has the appropriate architecture for controlling vascular tone and the findings throughout metamorphosis reveal that the vascular regulatory function begins at an early stage of metamorphosis. In addition, immunohistochemical studies suggest that the vascular regulation in the carotid labyrinth is under peptidergic innervation. Thus, the multiple functions of the carotid labyrinth underline the importance of this relatively small organ for maintenance of homeostasis and appropriate blood supply to the cephalic region.

Amphibians↗
PubMed2002

Loss of the ecdysteroid-inducible E75A orphan nuclear receptor uncouples molting from metamorphosis in Drosophila.

Isoform-specific null mutations were used to define the functions of three orphan members of the nuclear receptor superfamily, E75A, E75B, and E75C, encoded by the E75 early ecdysteroid-inducible gene. E75B mutants are viable and fertile, while E75C mutants die as adults. In contrast, E75A mutants have a reduced ecdysteroid titer during larval development, resulting in developmental delays, developmental arrests, and molting defects. Remarkably, some E75A mutant second instar larvae display a heterochronic phenotype in which they induce genes specific to the third instar and pupariate without undergoing a molt. We propose that ecdysteroid-induced E75A expression defines a feed-forward pathway that amplifies or maintains the ecdysteroid titer during larval development, ensuring proper temporal progression through the life cycle.

Animals↗
PubMed1993

Long-chain dietary fatty acids affect the capacity of Drosophila melanogaster to tolerate ethanol.

Four-day post-hatch larvae (mid-third instar) of Drosophila melanogaster were fed an intermediate diet with or without supplement of an individual fatty acid for 2 d and then transferred to a diet with a growth-limiting level of 0.94 mol/L ethanol (5.5%, v/v) or an ethanol-free diet. The ethanol stress decreased survival and larval development rate but increased the weight of surviving adult males. Dietary long-chain fatty acids altered the fatty acid composition of tissue lipids of larvae. When an unsaturated fatty acid was fed, except for 18:2(n-6), the tissue level of total unsaturated fatty acids was markedly increased. Both saturated and unsaturated 18-carbon fatty acids shortened larval development time. Linoleic acid [18:2(n-6)] and linolenic acid [18:3(n-3)] enhanced survival overall and, together with stearic acid (18:0), gave marked protection from ethanol stress in terms of survival. Correlation analysis across the different fatty acid diets indicated a strong positive association between tissue 18-carbon fatty acid levels and ethanol tolerance and between 18-carbon fatty acid levels and development rate. No major differences were observed in the effects of the fatty acids on the Canton-S and OD4 (Tahbilk) wild-type strains. Thus, the fatty acid content of D. melanogaster larvae is important for growth and survival in ethanol-rich habitats.

Animals↗
PubMed2001

Complexity in specificities and expression of Helicoverpa armigera gut proteinases explains polyphagous nature of the insect pest.

Helicoverpa armigera is a devastating pest of cotton and other important crop plants all over the world. A detailed biochemical investigation of H. armigera gut proteinases is essential for planning effective proteinase inhibitor (PI)-based strategies to counter the insect infestation. In this study, we report the complexity of gut proteinase composition of H. armigera fed on four different host plants, viz. chickpea, pigeonpea, cotton and okra, and during larval development. H. armigera fed on chickpea showed more than 2.5- to 3-fold proteinase activity than those fed on the other host plants. H. armigera gut proteinase composition revealed the predominance of serine proteinase activity; however, the larvae fed on pigeonpea revealed the presence of metalloproteases and low levels of aspartic and cysteine proteases as well. Gut proteinase activity increased during larval development with the highest activity seen in the fifth instar larvae which, however, declined sharply in the sixth instar. Over 90% of the gut proteinase activity of the fifth instar larvae was of the serine proteinase type, however, the second instar larvae showed the presence of proteinases of other mechanistic classes like metalloproteases, aspartic and cysteine proteases along with serine proteinase activity as evident by inhibition studies. Analysis of fecal matter of larvae showed significant increase in proteinase activity when fed on an artificial diet with or without non-host PIs than larvae fed on a natural diet. The diversity in the proteinase activity observed in H. armigera gut and the flexibility in their expression during developmental stages and depending upon the diet provides a base for selection of proper PIs for insect resistance in transgenic crop plants.

Animals↗
PubMed1999

Dose titration of an injectable formulation of lufenuron in cats experimentally infested with fleas.

OBJECTIVES: To identify the lowest single dose of lufenuron injected s.c. that results in a 90% disruption of the flea (Ctenocephalides felis) life cycle for 6 months in cats. ANIMALS: 40 domestic shorthair cats (20 males, 20 females) between 5 and 7 months old. PROCEDURE: Cats were randomly assigned to 1 of 5 eight-cat groups and experimentally infested with C. felis on days -8, -7, -6, and -4. On day 0, cats in the 4 treatment groups were treated with an injectable formulation of lufenuron at doses of 2.5, 5, 10, or 20 mg/kg of body weight, respectively. Control cats received the injectable formulation without lufenuron. Experimental infestations were repeated and flea eggs collected at various intervals for 196 days after treatment. Eggs were placed in media and incubated in an insectary for 28 days to determine effects of injectable lufenuron on egg and larval development. Number of adults that emerged from eggs were compared among groups. RESULTS: Lufenuron injected once at a dose of 10 or 20 mg/kg, but not at 2.5 or 5 mg/kg, resulted in a 90% decrease in number of adult fleas emerging from eggs for 196 days after treatment. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicate that control of flea egg and larval development for at least 6 months can be achieved in cats with a single s.c. injection of lufenuron (10 mg/kg). The injectable formulation may provide veterinarians and cat owners an alternative to the tablet formulation of lufenuron.

Animals↗
PubMed2005

Regulation of Oestrus ovis (Diptera: Oestridae) populations in previously exposed and naïve sheep.

Larvae of Oestrus ovis (Insecta: Diptera: Oestridae) are common parasites of nasal and sinus cavities of sheep and goats. During larval development, a specific immune reaction is initiated by the host with a humoral local and systemic response and the recruitment of eosinophils and mast cells in the upper airways mucosae. Nevertheless, the roles of these responses in the regulation of O. ovis larvae populations in sheep are not yet known. The aim of this study was to compare the establishment and the development of larvae as well as some inflammatory or immune parameters between different groups of half-sibling sheep: (i) a primed group experimentally infected twice before a challenge infection, (ii and iii) two groups infected once only and previously treated with a long-lasting corticoïd before the challenge (one group) or not (the other group). A fourth group of non-infected animals was added in the experimental design. The larval establishment rate was 23% in the corticoïd treated group compared to about 10% in the two other infected groups. Moreover, the larval development appeared more rapid in the corticoïd treated group than in the two other infected groups suggesting that the inflammatory response is involved in the regulation of O. ovis populations. By contrast, no differences in the establishment rates were shown in the primed group compared to the naïve group (without corticoïd treatment) despite evidence of higher eosinophilia, serum specific IgG, and immediate hypersensibility to excretory-secretory products of larvae. The specific lymphocyte proliferation was reduced in the primed group compared to the naïve one suggesting that an immuno-suppression occurs following repetitive O. ovis infections.

Adrenal Cortex Hormones↗